<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>语义化元素</title>
    <style>
    body
       {
          --space-lenth:100px;
          --color:red;
       }
       div
       {
         width: var(--space-lenth);
         height: var(--space-lenth);
         background-color: var(--color);
       }

       img
       {
         filter: blur(5px);
       }
    </style>
</head>
<body>
  <div>
    <img src="../image/bili.png" alt="">
  </div>
</body>
</html>